1. Technical Field
The disclosure relates to antennas for portable wireless communication devices, particularly, to a dual-band antenna which can provide dual frequency bands and a portable wireless communication device employing the dual-band antenna.
2. Description of Related Art
Antennas are important components of portable wireless communication devices, such as mobile phones and personal digital assistants (PDAs). The antennas are used to send and receive radio frequency signals. Today, most of the wireless communication devices use dual-band antennas or multi-band antennas to replace former single-band antenna for improving communicating quality. Referring to FIG. 5, a typical dual-band antenna 1 often includes a first radiation unit 11 and a second radiation unit 12. One end of the second radiation unit 12 is electrically connected to the first radiation unit 11, and the other end of the second radiation unit 12 is connected to the ground (GND). The first radiation unit 11 includes a first radiation part 111 and a second radiation part 112. The first radiation part 111 and the second radiation unit 12 together generate an antenna harmonic in a high frequency, and the second radiation part 112 and the second radiation unit 12 together generate an antenna harmonic in a low frequency.
Although the dual-band antenna 1 can operate in a dual-band, because the radiation units 11 and 12 of the dual-band antenna 1 share a grounding end, and the second radiation unit 12 is shared to generate the high frequency and the low frequency. Thereby, the size of the first radiation part 111 and the second radiation part 112 determines work bands of the dual-band antenna 1, so if the size of the first radiation part 111 or the second radiation part 112 is adjusted, then the size of the second radiation unit 12 need to be adjusted at the same time. Therefore, it is difficult for the dual-band antenna to have an independent and non-interferential resonant frequency, and also it is difficult to adjust the bandwidth.
Therefore, there is a room for improvement within the art.